Recently, in more and more cases, drive motors are mounted in vehicles in view of environmental concerns. Those vehicle-mounted drive motors are demanded for small footprint due to limited mounting space. Further, those motors are requested to output high power in order to enhance drive performance of the vehicles. In particular, a hybrid car has to mount therein both an engine and a drive motor in an engine room and is subjected to severe space limitations.
To reduce the size and increase output power of both a motor and a rotary electric machine, it is conceived to increase electric current values supplied to a coil provided in a stator. However, this needs a sufficient cross sectional area of a coil used in a stator and thus the use of a coil made of a flat rectangular conductor has been proposed. One of methods of forming such a coil of a flat rectangular conductor employs a segment coil. This method is achieved by forming segments by bending a flat rectangular conductor into a nearly U shape, inserting these segments in slots of a stator core, and then welding the segments to each other on a lead side of the stator to form a coil.
Patent document 1 discloses a technique related to a winding joining method of a rotary electric machine. When lead sections placed at a coil end of a stator are to be welded, an intermediate holding member is inserted between a second open end and a third open end from a radially inner circumference side of the lead sections. On the other hand, a first radial restricting member is pressed against an innermost circumferential open end from the radial inside and a second radial restricting member is pressed against an outermost circumferential open end from the radial outside. In addition, voltage is supplied between a torch and the members and inert gas is supplied to the torch, generating arc discharge between the torch and the open ends, thereby welding the open ends adjacent in the radial direction to each other. This can enhance welding property.
Patent document 2 discloses a technique related to a stator coil with sequentially joined segments of a rotary electric machine, and a manufacturing method thereof. A gap between lead sections protruding from an end face of a stator core is narrow in a radial direction on an end face side but wide in a radial direction on a tip side. This can enhance a lamination factor in each stator while preventing undesirable mutual contact of mutually adjacent tip portions and slat portions of the end parts and deterioration of insulation resistance.